SUWON — A new habitat of the white-clawed fiddler crab, a Class II endangered wild species and a protected marine species in South Korea, has been confirmed for the first time on the tidal flat of Daebudo Island in Ansan, Gyeonggi Province.
Gyeonggi Province said on the 20th that its Fisheries and Marine Resources Research Institute discovered the habitat during an ecological survey of the province's tidal flats that began in June, in an area with no previous record of the species.
Two separate habitats were identified, measuring about 1,600 square meters and 1,000 square meters, for a combined area of roughly 2,600 square meters. Based on an analysis of population density at the site, the institute estimated that at least 30,000 white-clawed fiddler crabs live there.
The white-clawed fiddler crab is a small crab that lives mainly in the upper intertidal zone of tidal flats, closer to land. Males have one claw that is disproportionately large and white. The species is classified as requiring protection after its numbers declined due to tidal flat development and habitat loss.
The institute obtained permits from the Ministry of Environment and the Ministry of Oceans and Fisheries to collect a minimal number of specimens. It then confirmed the species through a study of morphological features and DNA analysis.
The survey also found egg-bearing females and juveniles. On that basis, the institute concluded that the crabs are not appearing temporarily on the Daebudo tidal flat but are breeding and sustaining a population there.
The institute and the Ansan city government plan to take on-site protection steps, including installing information signs. They will also review management measures to prevent damage to the habitat from public access and use of the tidal flat.
The survey additionally confirmed a small habitat of another protected marine species, the pea crab species Pyrhila pisum. The institute previously surveyed habitats of that species within the province in 2022 and 2023. Gyeonggi Province said it will continue to track the presence of rare and protected species on its tidal flats.
"This discovery shows that Gyeonggi Province's tidal flats are an important ecological space where diverse organisms live," said Kim Seong-gon, head of the Gyeonggi Fisheries and Marine Resources Research Institute. "We will work with the Ansan city government to steadily monitor changes in the habitat and population of the white-clawed fiddler crab and continue field-based protection activities."